While it is known that in the neuromuscular disorder FRDA, the decreased iron-sulphur cluster and heme formation by defective frataxin protein causes the pathological accumulation of redox-active labile iron in mitochondrial compartments (Rouault 2016; Llorens et al. 2019; Chiang et al. 2020), our study was the first to provide an estimate of the extent of mitochondrial iron overload in cells derived from FRDA patients. Here, FXN is linked to Friedreich ataxia.